Method of treating wood for use with alcoholic beverages

ABSTRACT

A cask for storing alcoholic beverage is made of a pre-treated wooden material, such as oak wood, wherein the method of pre-treatment includes soaking the wood in a salt solution and heating or toasting the wood thereafter to produce a color change in the wood. Is has been found that impregnating the wood with salt extracts is beneficial in respect of flavoring and coloring the alcoholic beverage.

This invention relates to a method for treating cask oak wood or otherwood products used to enhance the flavour of alcoholic beverage andfurthermore to provide colour improvement of such beverage.

Traditionally oak has been used for the manufacture of casks for storingalcoholic beverages, such as spirits and wines. The casks are made fromshaped oak wood blocks which may be heat treated to provide particularflavouring and colour characteristics to the beverage which is to beheld in the cask. In addition other oak wood products, for example, oakblocks, shavings or extracts have been added to alcoholic beverages toprovide particular flavour or colour characteristics.

It has been known to treat the oak with metal salts, particularly forthe purpose of providing tire retardants.

An object of the present invention, however, is to use salt and simpleorganic compound solutions for the purposes of providing flavour andcolour to the alcoholic beverage.

According to the invention there is provided a cask for containingalcoholic beverages, the cask being made from wood which has beenimpregnated with a salt or compound solution.

Preferably, the wood is oak. The oak may be provided in the form ofwooden blocks which may be soaked in the solution.

Preferably also of the wood blocks are heat treated after their soakingin the solution.

Also according to the invention there is provided oak wood impregnatedwith salt extracts for storing, flavouring or colouring alcoholicbeverages.

According to a further aspect of the invention there is provided amethod of manufacturing casks for containing alcoholic beverages, themethod including the steps of:

a) soaking wood blocks for a period, the length of which is dependant onthe degree of colour and flavour change required; and

b) heat treating the wood blocks for a period and at a temperature whichwill develop the required colour and flavour.

Also according to the invention the above method may be used in respectof oak wood products used for flavour or colouring alcoholic beverages(e.g. wood shavings, oak blocks or oak extracts).

In order to assist the reader in performing the invention, the followingexample is given. That is, oak wood may be soaked overnight in asolution of a compound or a solution of a mixture of compounds, inaccordance with the invention. By way of example only, the followingcompounds may be used; calcium chloride, magnesium sulphate, potassiumdihydrogen phosphate, dipotassium hydrogen phosphate, urea, sodiumchloride, potassium chloride, magnesium chloride, iron chloride, sodiumsulphate, zinc sulphate, sodium dihydrogen phosphate, disodium hydrogenphosphate and glycine.

After the oak wood have been soaked in the solution, it may be toastedat 190° C. for 60 minutes. It is preferable although not essential thatthe toasting of the wood takes place after the soaking process.Similarly, the temperature and time of the toasting process should besimilar to that which would be found in a cooperage.

Experiments have been conducted using this process in respect of varioussolutions and the results of the experiment may be seen from theattached table. In the experiment the surface of the blocks were removedto a depth of 3 mm and an ethanol/water extract was made of the woodflour. These extracts were presented blind to a sensory panel of 7people for assessment. They scored the extracts for a flavour aroma (thescores being from 0 to 3) and the main scores are presented in the tableattached. Colour of the extracts (at 60% v/v ethanol) were measured witha spectrophotometer at 430 nm.

It may be seen from the attached table that large differences betweenthe controls (the untreated and heat treated only rows) were observed inrespect of both flavour profiles and colour intensity. This is truewhether individual compounds in the treatments were employed or where,alternatively, a mixture was employed.

It may also be seen from the experiment described above that the use ofdifferent salts and solutions may be selected to achieve a desired andpredetermined result in respect of colour and flavour. Various flavouraromas may be achieved depending on the choice of solution and thus theinvention may be used for a wide variety of alcoholic spirits and wines.

The invention provides considerable commercial advantages over processesknown herebefore. For example, in some whiskies and other beverages itis very desirable to darken the colour. Previously, this may have beenachieved by adding colouring, such as caramel which may be associatedwith undesirable taste characteristics. The present invention isadvantageous over such a process in that it does not require an additiveto be provided directly to the beverage itself.

Furthermore, the invention is suitable where casks are regenerated. Acask which has been previously used to contain alcoholic beverage may,after use, be shaved, treated (e.g. soaked in a solution) and heattreated. Treatment of a pre-used cask may be simply by filling the caskwith a desired salt solution and leaving it to rest for a pre-determinedperiod, such as overnight.

Further modifications may be incorporated without departing from thescope of the invention herein intended.

    __________________________________________________________________________    Wood Treatments                    Mean scores of flavour aromas          Colour    Compound/toast  TIA Burnt sugar                              Burnt wood                                    Vanilla                                        Buttery                                             Coconut                                                 Woody                                                      Spicey                                                           (EBC    __________________________________________________________________________                                                           units)**    Untreated/untoasted                    1.5 0.8   0.3   0.7 0.4  0.3 1.5  0.4  30.3    MgSO.sub.4 /190° C., 60 mins.                    1.6 1.0   0.6   0.6 0.8  0.0 1.0  0.5  41.3    Untreated/190° C., 60 mins.                    2.0 1.5   0.9   0.6 0.3  0.0 1.4  0.1  42.8    KH.sub.2 PO.sub.4 /190° C., 60 mins.                    1.8 1.3   0.8   1.4 0.5  0.0 0.6  0.9  45.9    Mix*/190° C.,60 mins.                    1.5 1.0   0.6   1.3 0.3  0.1 1.6  0.6  51.4    CaCl.sub.2 /190° C., 60 mins.                    2.4 2.3   1.1   1.8 0.4  0.3 0.5  0.5  67.6    Urea(CH.sub.4 N.sub.2 O)/190° C., 60 mins.                    2.1 1.0   1.5   0.9 0.3  0.5 0.3  0.5  71.3    K.sub.2 HPO.sub.4 /190° C., 60 mins.                    1.4 1.3   1.3   1.0 0.5  0.0 0.8  0.6  83.1    __________________________________________________________________________     *Mix: MgSO.sub.4     KH.sub.2 PO.sub.4     CaCl.sub.2     Urea     K.sub.2 HPO.sub.4     **EBC units: European Brewery Convention  units read at 430 nm on a     spectrophotometer, multiplied by 25.

We claim:
 1. A wood product for enhancing the flavor and color ofalcoholic beverages, the wood product being made from wood which hasbeen impregnated with a salt solution and then heat treated to cause acolor change in the wood and add flavors thereto.
 2. A wood productaccording to claim 1, wherein the wood is oak.
 3. A wood productaccording to claim 1, wherein the heat treatment is comprised oftoasting.
 4. A wood product according to claim 1, wherein the woodproduct is a cask for containing alcoholic beverages.
 5. A wood productaccording to claim 1, wherein the wood product is in the form of oakwood shavings.
 6. A method of treating wood for use in manufacturingcasks for containing alcoholic beverages, the method including the stepsof:a) soaking wood blocks in a salt solution for a period of time so asto impregnate said wood blocks with said salt solution, the length ofsaid period of time being dependent on the degree of color and flavorchange required in the alcoholic beverage; and b) subsequently heattreating said wood blocks to cause a color change in said wood blocksfor a period of time and at a temperature which will develop therequired degree of color and flavor change in the alcoholic beverage. 7.A method according to claim 6, wherein the wood blocks are oak.
 8. Amethod according to claim 6, wherein the heat treating is comprised oftoasting.